Effectively, event-driven programming puts the task of sorting out process scheduling into the hands of the developer, rather than the OS, which would otherwise

Effectively, event-driven programming puts the task of sorting out process scheduling into the hands of the developer, rather than the OS, which would otherwise have to guess at the best scheduling approach. Yes, there are also speed advantages from losing the context switch overhead, but fundamentally, I believe it is the programmer-controlled scheduling that makes event driven apps faster, all other things being held equal.